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Study: Viruses linked to AFM :

October 8, 2019

Enteroviruses and other viruses likely play a role in the development of acute flaccid myelitis (AFM), according to a new study.

AFM is rare but serious, characterized by sudden limb weakness and typically preceded by respiratory illness or fever. Federal health officials have been trying to pinpoint a cause of outbreaks, the largest of which have been occurring every other year since 2014.

In 2014, AFM cases coincided with a nationwide outbreak of enterovirus D68 (EV-D68) but the Centers for Disease Control and Prevention (CDC) could not conclusively say it was the cause and has continued to investigate.

In a new study, the CDC analyzed data on 193 confirmed pediatric AFM cases from 2015-’17. Consistent with previous research, most of the cases were in 2016 and typically were seen in August through November, according to “Acute Flaccid Myelitis in the United States: 2015-2017,” (Ayers T, et al. Pediatrics. Oct. 7, 2019,

In those ages 21 and under, the virus struck about 2.13 people per million. About 61% were male and the median age was 6 years. Other findings include:

  • 79% had respiratory or febrile illness before experiencing limb weakness;
  • 80% had lesions in their cervical spine;
  • 47% had a pathogen detected;
  • one patient had coxsackievirus A16 detected in cerebrospinal fluid and serum;
  • one patient had EV-D68 detected in serum; and
  • 28% of respiratory and stool specimens were positive for enterovirus/rhinovirus.

“We conclude that symptoms of a viral syndrome within the week prior to limb weakness, detection of viral pathogens from sterile and non-sterile sites from almost half of patients, and seasonality of AFM incidence particularly during the 2016 peak year strongly suggest a viral etiology, including enteroviruses,” authors wrote.

Because most children with an enterovirus or rhinovirus do not progress to AFM, authors noted more research is needed to determine whether a virus directly attacks the central nervous system or if an immune response plays a role.

“Additional studies are needed to assess risk factors, establish causality, and develop a more comprehensive understanding of the mechanisms that lead to AFM,” they wrote.

Since tracking began in 2014, there have been 590 cases of AFM, including 22 this year in California, Georgia, Maryland, Nebraska, North Carolina, Pennsylvania, Texas, Utah and West Virginia. Physicians who suspect a patient has AFM should perform a workup, including MRI and collection of respiratory, stool, serum and spinal fluid samplesfor testing. They also should quickly report suspected cases to their state or local health department.

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